Color diffusion transfer film units comprising a layer which contains a synthetic polymer-benzenoid silver halide developing agent complex and process for their use

ABSTRACT

THE PRESENT INVENTION RELATES TO PHOTOGRAPHY AND, MORE PARTICULARLY, TO DIFFUSION TRANSFER PROCESS PHOTOGRAPHIC FILM UNITS WHICH COMPRISE A PHOTOSENSITIVE ELEMENT ADAPTED TO PROVIDE, BY DIFFUSION TRANSFER PHOTOGRAPHIC PROCESSING, SELECTIVE DYE IMAGE RECORDATION OF INCIDENT ACTINIC RADIATION AS A FUNCTON OF THE POINT-TO-POINT DEGREE OF PHOTOSENSTIVE ELEMENT EXPOSURE, WHICH FILM UNIT INCLUDES A PLURALITY OF ESSENTIAL LAYERS INCLUDING A PHOTOSENSITIVE SILVER HALIDE LAYER HAVING ASSOCIATED THEREWITH DYE DEVELOPER, I.E., A DYE WHICH IS A SILVER HALIDE DEVELOPING AGENT, WHICH IS DIFFUSIBLE DURING PROCESSING AS A FUNCTION OF THE POINT-TO- POINT DEGREE OF SILVER HALIDE LAYER EXPOSURE TO INCIDENT ACTINIC RADIATION AND A LAYER ADAPTED TO RECEIVE IMAGE-FORMING MATERIAL DIFFUSING THERETO, AT LEAST ONE OF THE LAYERS OF THE FILM UNIT COMPRISING A PARTICULATE DISPERSION OF A SYNTHETIC POLYMER-SILVER HALIDE DEVELOPING AGENT COMPLEX DISSOCIABLE AS A FUNCTION OF PH TO PROVIDE A PROCESSING COMPOSITION SOLUBLE SILVER HALIDE DEVELOPING AGENT; AND TO SPECIFIED DIFFUSION TRANSFER PROCESSES EMPLOYING SUCH FILM UNITS.

Dec. 26, 1912 D. J. RASMUSSEN E 3 COLOR DIFFUSION TRANSFER FILM UNITS COMPRISING A LAYER WHICH CONTAINS A SYNTHETIC PQLYMERBENZENOID SILVER HALIDE DEVELOPING AGENT COMPLEX AND PROCESS FOR THEIR USE 4 Sheets-Sheet 1 Filed Anril 19. 1971 INVENTORS DIM ITE J. RASMUSSEN and BY PETER H. ROTH 31mm and mm wml 290M 772. 396d ATTORNEYS Dec. 26, J RASMUSSEN FF AL COLOR DIFFUSION TRANSFER FILM UNITS COMPRISING A LAYER WHICH CONTAINS A SYNTHETIC POLYMER-BENZENOID SILVER HALIDE DEVELOPING AGENT COMPLEX AND PROCESS FOR THEIR USE Filed April 19. 1971 4 Sheets-Sheet 2 INVENTORS DEMITE J. RASMUSSEN and BY PETER H. ROTH E/Loum and M 01ml Ar TOHNI YS 4 Sheets-Sheet :5

INVENTORS DIMITE J. RASM USSEN PETER H. ROTH AT TORNE Y5 DQC. 26, 1972 J RASMUSSEN ETAL" COLOR DIFFUSION TRANSFER FILM UNITS COMPRISING A LAYER WHICH CONTAINS A SYNTHETIC POLYMER-BENZENOID SILVER HALIDE DLVELOPING AGENT COMPLEX AND PROCESS FOR THEIR USE Filed April 19, 1971 mum/2 Dec. 26, 1972 J R s ss ETAL 3,707,310

COLOR DIFFUSION TRANSFER FILM UNITS COMPRISING A LAYER WHICH CONTAINS A SYNTHETIC POLYMER-BENZENOID SILVER HALIDE DEVELOPING AGENT COMPLEX AND PROCESS FOR THEIR USE Filed April 19. 1971 4 Sheets-Sheet 4.

INVENTORS DIMITE :LRASMUSSEN 0 BY PETER H ROTH 15mm 2% M MJJ/IL Z/aul A T TURN! Y3:

United States Patent COLOR DIFFUSION TRANSFER FILM UNITS COM- PRISING A LAYER WHICH CONTAINS A SYN- THETIC POLYMER-BEN ZEN OID SILVER HALIDE DEVELOPING AGENT COMPLEX AND PROCESS FOR THEIR USE Dimite J. Rasmussen, Concord, and Peter H. Roth, Needham, Mass, assignors to Polaroid Corporation, Cambridge, Mass.

Filed Apr. 19, 1971, Ser. No. 135,210 Int. Cl. G03c 7/00, /54, 1/48 US. Cl. 96-3 25 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to photography and, more particularly, to diffusion transfer process photographic film units which comprise a photosensitive element adapted to provide, by diffusion transfer photographic processing, selective dye image recordation of incident actinic radiation as a functon of the point-to-point degree of photosenstive element exposure, which film unit includes a plurality of essential layers including a photosensitive silver halide layer having associated therewith dye developer, i.e., a dye which is a silver halide developing agent, which is diffusible during processing as a function of the point-topoint degree of silver halide layer exposure to incident actinic radiation and a layer adapted to receive image-forming material diffusing thereto, at least one of the layers of the film unit comprising a particulate dispersion of a synthetic polymer-silver halide developing agent complex dissociable as a function of pH to provide a processing composition soluble silver halide developing agent; and to specified diffusion transfer processes employing such film units.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention is directed to providing new and improved diffusion transfer process photographic film units adapted to provide, as a function of the point-to point degree of photoexposure, by diffusion transfer processing a dye transfer image.

(2) Description of prior art As disclosed in US. Pat. No. 3,415,644, a composite photosensitive structure, particularly adapted for reflection type photographic diffusion transfer color process employment, which comprises a plurality of essential layers including, in sequence, a dimensionally stable opaque layer; one or more silver halide emulsion layers having associated therewith dye image-providing material which is soluble and diffusible, in alkali, at a first pH, as a function of the point-to-point degree of its associated silver halide emulsions exposure to incident actinic radiaton; a polymeric layer adapted to receive solubilized dye image-providing material diffusing thereto; a polymeric layer containing sufficient acidifying capacity to effect reduction of a processing composition from the first pH to a second pH at which the dye image-providing material is substantially nondiffusible; and a dimensionally stable transparent layer, may be exposed to incident actinic radiation and processed by interposing, intermediate the silver halide emulsion layer and the reception layer, an alkaline processing composition possessing the first pH and containing opacifying agent, which may reflect incident radia tion, in a quantity sufficient to mask dye image-providing material associated with the silver halide emulsion.

In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining 3,707,370 Patented Dec. 26, 1972 the alkaline processing composition having the first pH and opacifying agent, fixedly positioned extending transverse a leading edge of the composite structure in order to effect, upon application of compressive pressure to the container, discharge of the processing composition intermediate the opposed surfaces of the reception layer and the next adjacent silver halide emulsion.

The liquid processing composition, distributed intermediate the reception layer and the silver halide emulsion, permeates the silver halide emulsion layers of the composite photosensitive structure to initiate development of the latent images contained therein resultant from photoexposure. As a consequence of the development of the latent images, dye image-providing material associated with each of the respective silver halide emulsion layers is individually mobilized as a function of the point-topoint degree of the respectve silver halide emulsion layers photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diffusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, a sufficient portion of the ions of the alkaline processing composition transfers, by diffusion, to the polymeric neutralizing layer to etfect reduction in the alkalinity of the composite film unit to the second pH at which dye image-providing material is substantally nondilfusible, and further dye image-providing material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the opacifying agent, distributed as a component of the processing composition, intermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed opacifying stratum effectively masks residual dye image-providing mate rial retained in association with the silver halide emulsion layer subsequent to processing.

In US. Pat. No. 3,415,646, the dimensionally stable layer of the film unit next adjacent the photosensitive silver halide layer or layers is disclosed to be transparent to incident actinic radiation and as disclosed in US. Pat. No. 3,415,645, in such instance the opacifying agent may be initially disposed in the film unit intermediate the reception layer and next adjacent silver halide layer.

As disclosed in the copending US. patent application Ser. No. 846,441 of Edwin H. Land, filed July 31, 1969, now US. Pat. No. 3,615,421, and the copending US. patent application Ser. No. 3646 of Sheldon A. Buckler, filed Jan. 19, 1970, now US. Pat. No. 3,661,585 the opacifying component of the film unit may optionally be initially disposed as a preformed processing composition permeable layer, intermediate the reception layer and next adjacent silver halide layer, in a concentration which prior to photoexposure is insufficient to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye image-providing material retained associated with the film units silver halide emulsion layers, and in the copending US. patent application Ser. No. 43,742 of Edwin H. Land, filed June 5, 1970, now US. Pat. No. 3,647,435, the opacifying component .of the film unit may optionally be initially formed in situ, intermediate the reception layer and next adjacent silver halide layer, during photographic processing of the film unit.

In the copending US. patent applications of Edwin H. Land, Ser. No. 786,352, filed Dec. 23, 1968, and Ser. No. 43,782, filed June 5, 1970, abandoned and replaced by US. Pat. No. 3,647,437, the opacifying component is disclosed to optionally comprise a light-absorbing reagent such as a dye which is present as an absorbing species at the first pH and which may be converted to a substantially non-absorbing species at the second pH, and in U.S. Pats. Nos. 3,473,925 and 3,573,042 and the copending U.S. patent application of Terry W. Milligan and Richard W. Young, Ser. No. 864,397, filed Oct. 7, 1969, now U.S. Pat. No. 3,576,626, opacifying and reflecting component, respectively, may be individually interposed intermediate the silver halide layer and reception layer by selective distribution from a composite or a plurality of rupturable containers.

In U.S. Pat. No. 3,573,043, the polymeric neutralizing layer is disclosed to be optionally disposed intermediate the' dimensionally stable opaque layer and next adjacent essential layer, i.e., next adjacent silver halide/dye imageproviding material component, to effect the designated modulation of film units environmental pH; the copending U.S. patent application Ser. No. 846,442 of Edwin H. Land, filed July 31, 1969, now U.S. Pat. No. 3,576,625 discloses the employment of particulate acid distributed within the film unit to effect the modulation of the environmental pH, and U.S. Pat. No. 3,573,044 discloses the employment of processing composition solvent vapor transmissive dimensionally stable layers to effect process modulation of dye transfer as a function of solvent concentration.

Where desired, the film unit may also be constructed in accordance with the disclosure of the copending U.S. patent applications of Howard G. Rogers, Ser. No. 39,646, filed May 22, 1970, now U.S. Pat. No. 3,594,165, and Ser. No. 39,666, filed May 22, 1970, now U.S. Pat. No. 3,594,- 164, to comprise a composite photosensitive structure including a transparent dimensionally stable layer carrying a reception layer, a processing composition permeable opaque layer and a photosensitive silver halide layer and the film unit may include a separate dimensionally stable sheet element adapted to be superposed on the surface of the photosensitive structure opposite the dimensionally stable layer and may further include means such as a rupturable container retaining processing composition for distribution of a processing composition intermediate the sheet and photosensitive structure to effect processing. As further disclosed in the last-cited applications, in structures wherein the receptor is positioned next adjacent the transparent layer or the processing composition and/ or the sheet is to be separated from the remainer of the film unit subsequent to processing, the latter elements may optionally include opacifying component.

As disclosed in copending U.S. patent application Ser. No. 3645 of Edwin H. Land, filed Jan. 19, 1970, now U.S. Pat. No. 3,620,724, the dimensionally stable layer referred to may be opaque and in which instance the photosensitive silver halide layer is positioned next adjacent the opaque support layer and the opacifying component of the film units processing composition permeable opaque layer will be disposed in the unit in a concentration insufficient to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye imageproviding material retained associated with the silver halide layer, and as disclosed in the copending U.S. patent application Ser. No. 43,741 of Edwin H. Land, filed June 5, 1970, now U.S. Pat. No. 3,647,434, the opacifying agent may be optionally formed in such film unit, in stiu, during processing of the unit.

As disclosed in each of the U.S. patents and applications cited above and in U.S. Pats. Nos. 3,146,102; 3,192,- 044; 3,253,915; 3,260,597; and the like, an auxiliary or accelerating silver halide developing agent, for example, p-methylaminophenol, 2,4-diaminophenol, 2-benzylaminophenyl, hydroquinone, toluhydroquinone, phenylhydroquinone, 4'-methylphenylhydroquinone, etc., may be advantageously employed for color image reproduction by dye diffusion transfer photographic processes and may include the employment of a plurality of auxiliary or ac- 4 I celerating developing agents, such as a 3-pyrazolidone developing agent and a benzenoid developing agent, as disclosed in U.S. Pat. No. 3,039,869. As examples of suitable combinations of auxiliary developing agents, mention is there made of 1-phenyl-3-pyrazolidone in combination with p-benzylaminophenol and 1-phenyl-3-pyrazolidone in combination with 2,5 bis-ethylenimino-hydroquinone. Such auxiliary developing agents are disclosed to be employed in the liquid processing composition or initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layer, the image-receiving layer, or in any other auxiliary layer, or layers, of the film unit, and at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energy-transfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer is understood to regenerate the auxiliary developing agent for further reaction with the exposed silver halide.

SUMMARY OF THE INVENTION The present invention is directed to a new and improved, preferably integral negative/positive, diffusion transfer process photographic film unit adapted to provide, by diffusion transfer processing, photographic color image reproduction as a function of exposure of such film unit to incident actinic radiation.

The film unit assemblage construction to be employed in the practice of the present invention preferably comprises a film unit of the general type set forth in aforementioned U.S. Pats. Nos. 3,415,644, -5, and -6; 3,473,- 925; 3,573,042, -3, and -4; and copending U.S. patent applications Serial Nos. 786,352, abandoned and replaced by U.S. Pat. No. 3,647,437; 846,441, now U.S. Pat. No. 3,615,421; 846,442, now U.S. Pat. No. 3,576,625; 864,- 397, now U.S. Pat. No. 3,576,626; 3,645, now U.S. Pat. No. 3,620,724; 3691, now abandoned; 39,646, now U.S. Pat. 3,594,165; 39,666, now U.S. Pat. No. 3,594,164; 43,- 741, now U.S. Pat. No. 3,647,434; 43,742, new U.S. Pat. 3,647,435; and 43,782, abandoned and replaced by U.S. Pat. No. 3,647,437 and in U.S. Patents Nos. 2,983,606 and 3,345,163; and will include a photosensitive element adapted to provide, by diffusion transfer photographic processing, selective dye image recordation of incident actinic radiation as a function of the point-to-point degree of photo-exposure and which includes a plurality of layers including a photosensitive silver halide layer having associated therewith dye developer which is diffusible during processing, as a function of the point-to-point degree of the silver halide layers exposure to incident actinic radiation, and a layer adapted to receive dye developer diffusing thereto, at least one of the layers of the element comprising a particulate dispersion of a synthetic polymersilver halide developing agent complex dissociable as a function of pH to provide a processing composition soluble silver halide developing agent.

In one preferred embodiment, the film unit assemblage will comprise an integral negative/positive photosensitive element which contains a plurality of layers including a dimensionally stable layer; one or more photosensitive silver halide layers having associated therewith dye developer which is processing composition diffusible as a function of the point-to-point degree of photosensitive layer photoexposure; a layer adapted to receive dye developer diffusing thereto; means for interpositioning of opacifying agent intermediate the reception layer and next adjacent silver halide layer; a dimensionally stable layer transparent to actinic radiation; and means for contacting the silver halide layer with processing GQmposition, at least one of the film unit layers specifically including a particulate dispersion of a synthetic polymer-silver of pH to provide an active processing composition soluble halide developing agent complex dissociable as a function silver halide developing agent and, in particular, a construction which includes, in relative order, a dimensionally stable layer preferably opaque to incident actinic radiation; one or more photosensitive silver halide layers having associated therewith the aforementioned dye developer; a layer adapted to receive image-forming material dilfusing thereto; a dimensionally stable layer transparent to incident actinic radiation; and means for interposing, intermediate the silver halide layers and the reception layer, opacifying agent and a processing composition, and, in a particularly preferred embodiment, a processing composition possessing a first pH at which the dye developer is diffusible during processing and means for modulating the pH of the film unit from the first pH to a second pH at which the dye developer is substantially nonditfusible subsequent to substantial dye transfer image formation.

In accordance with a specifically preferred embodiment of the present invention, a film unit assemblage of the aforementioned general structural parameters will be adapted to be processed, subsequent to photoexposure, in the presence of actinic radiation and with respect to the last-mentioned preferred embodiment may be fabricated to employ, as means interposed intermediate the reception layer and next adjacent silver halide layer subsequent to photoexposure, an inorganic light-reflecting pigment dispersion containing reflecting pigment and at least one optical filter agent, at a pH above the pKa of the optical filter agent and at which pH the dye image-forming material is diffusible during processing as a function of silver halide layer photoexposure, in a concentration in admixture effective to provide a barrier to transmission of actinic radiation therethrough, and the means for interposing the opacifying agent and the processing composition, a rupturable container, retaining the opacifying agent disposed in the processing composition selected, fixedly positioned extending transverse a leading edge of the film unit and adapted, upon application of compressive pressure, to distribute its contents intermediate the reception layer and next adjacent silver halide layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a photographic film unit embodying the invention;

FIGS. 2, 4 and 6 are diagrammatic enlarged crosssectional views of the film unit of FIG. 1, along section line 2-2, illustrating the association of elements during the three illustrated stages of the performance of a diffusion transfer process, for the production of a multicolor transfer image according to the invention, the thickness of the various materials being exaggerated, and wherein FIG. 2 represents an exposure stage, FIG. 4 represents a processing stage and FIG. 6 represents a product of the process, and

FIGS. 3, and 7 are diagrammatic, further enlarged cross-sectional views of the film unit of FIGS. 2, 4 and 6, along section lines 33, 5--5 and 7--7, respectively, further illustrating, in detail, the arrangement of layers comprising the photosensitive laminate during the three illustrated stages of the transfer process.

DETAILED DESCRIPTION OF THE INVENTION As previously characterized, diffusion transfer photographic processing may be employed to provide a positive reflection dye image, as a direct function of actinic radiation incident on a film unit assemblage Which unit is preferably constructed to comprise a plurality of sequential layers including a dimensionally stable layer most preferably opaque to incident radiation; a photosensitive silver halide layer having associated therewith dye developer which is processing composition ditfusible at a selected first pH as a function of the point-to-point degree of silver halide layer photoexposure; a layer adapted to receive dye developer diffusing thereto; a dimensionally stable layer transparent to incident radiation; means for interposing, intermediate the silver halide layer and the reception layer, opacifying agent and preferably an inorganic reflecting pigment dispersion containing at least one optical filter agent or dye in a concentration effective to provide, subsequent to selective photoexposure of the silver halide layer, protection of the silver halide layer from further exposure to actinic radiation incident on the dimensionally stable layer; and means for converting the pH of the film unit from the first pH to a second pH at which the dye developer is substantially nondilfusible subsequent to substantial dye developer diffusion to the reception layer.

It now has been discovered, however, that improved photographic reproduction in color by diffusion transfer processing may be accomplished by employment of a diffusion transfer process film unit which comprises a plurality of layers including a photosensitive layer comprising photosensitive silver halide having associated therewith a dye developer which is diffusible, during processing of the unit, as a function of the point-to-point degree of the photosensitive layers exposure to incident actinic radiation, and a layer adapted to receive dye developer diffusing thereto, wherein at least one layer of the film unit and preferably one or more silver halide layers of the unit include a particulate dispersion of a synthetic polymer-silver halide developing agent complex substantially insoluble as disposed in the unit, e.g., substantially insoluble and nondissociable in aqueous media at a relatively neutral pH, and dissociable as a function of pH, e.g., upon contact with aqueous alkaline processing composition, to provide a processing composition soluble silver halide developing agent.

In particular, the polymeric complex will comprise a benzenoid silver halide developing agent, i.e., an aromatic silver halide developing agent which forms quinonoid or quinone oxidation products upon oxidation directly or indirectly resulting from reduction of photoexposed silver halide, e.g., an aromatic ring system such as a benzene or naphthalene ring system comprising at least two ring system substituents selected from the class consisting of hydroxyl and amino groups, at least one of the substituents substituted in at least one of ortho and para positions with respect to one other of the substituents, hydrogen bonding to a synthetic polymer through at least one of its hydroxyl or amino groups thereby substantially inactivating the silver halide developing potential of the benzenoid developing agent. Such hydrogen bonds being readily broken by input of about 8 to 10 Kcal., which may be directly provided by the approximately 13 Kcal. generated as a function of neutralization reactions coincident upon contact between the film unit and aqueous alkaline processing composition during the diffusion transfer process, thus providing the required active silver halide developing species desired during transfer processing.

The desired synthetic polymer-silver halide developing agent complexes may be readily prepared in a plurality of expeditious manners including dissolving a synthetic polymer, adapted to complex with the developing agent, in an aqueous and/or organic solvent in which the complex is substantially insoluble, dissolving and/or dispersing the developing agent in the medium and separating the resultant polymer-silver halide developing agent complex precipitate from the medium; dissolving the polymer in a first solvent medium and the developing agent in a second solvent medium, combining the respective mediums to provide the complex in a medium in which it is insoluble, and separating the resultant precipitate; intermixing dispersion of the respective components and solvent extracting non-complexed reactants; etc.

As examples of benzenoid silver halide developing agents contemplated for employment, in accordance with the present invention, mention may be made of:

phenylhydroquinone; 2'-hydroxyphenylhydroquinone; phenoxyhydroquinone; 4'-methylphenylhydroquinone; 1,4'-dihydroxynaphthalene; 2-(4-aminophenethyl)-5-brornohydroquinone; 2- 4-aminophenethyl -5-methylhydr0quin0ne; 4'-aminophenethylhydroquinone; 2,5-dimethoxyhydroquinone; 2,S-dibutoxyhydroquinone; m-xylohydroquinone; bromohydroquinone; 3,6-dichlorohydroquinone; Z-dimethylaminomethyltoluhydro quinone; 2-cyclohexylhydroquinone;

sec. butylhydroquinone; 2,5-dichlorohydroquinone; 2,S-diisopropylhydroquinone; 2,5-diiodohydroquinone; 3-chlorotoluhydroquinone; tetrachlorohydroquinone; 2,S-diphenylhydroquinone; 2,5-diresorcylhydroquinone; 2,5-dioctylhydroquinone; dodecylhydroqninone; p-methylaminophenol; 2,4-diarninophenol;

p-benzylaminophenol;

p-aminophenol;

hydroquinone, etc.

In general, the selected developing agent will preferably exhibit substantially no color, low solubility in the medium of the film unit at its storage pH, e.g., traditionally an aqueous system exhibiting a relatively neutral pH, and substantial solubility and mobility in the processing medium selected to elfect processing of the film unit, e.g., traditionally an aqueous system possessing an alkaline pH adapted to effect ionization of the phenolic hydroxyl groups of the preferred class of silver halide developing agents.

As examples of synthetic homo and copolymers contemplated for employment, in accordance with the present invention, mention may be made of polymers adapted to hydrogen bond with the hydroxyl and amino groups of the benzenoid silver halide developing agent through hydrogen bonding carbonyl groups such as, for example, oxazolidinone polymers such as poly-N-vinyl-S-methyl- 2-oxazolidinone commercially available from the Dow Chemical Company, Midland, Michigan under the trade name Devlex Resins; pyrrolidone polymers such as polyvinylpyrrolidone commercially available from GAF Corporation, Binghamton, New York; copolymeric pyrrolidone polymers such as polyvinyl alcohol/polyvinylpyrrolidone copolymers, polyvinylacetate/polyvinylpyrrolidone copolymers, acetal copolymers of polyvinyl pyrrolidones such as those of the formulae:

wherein R is an alkyl or aryl group, and the like; hydro gen bonding amine and imine groups such as polymers of the formulae:

CHr-CI-I l CHr-CH-NH wherein R is an alkyl group, and copolymers including such segments, and the like; hydrogen bonding amide and imide including sulfonamide and imide groups such as, for example, polyacrylamide, polymethacrylamide, and c0- polymeric and terpolyrneric materials containing such functional segments, and the like; hydrogen bonding carboxylate groups such as, for example, polyacrylic acid, polymethacrylic acid, and copolymeric and terpolymeric materials containing such functional segments, and the like; hydrogen bonding carbonate groups such as, for example, diethylene glycol bis allyl carbonate, polyvinylene carbonate, and copolymeric materials containing such functional segments, and the like; hydrogen bonding aldehyde groups such as copolymers of the formula:

wherein R is H or alkyl, and the like; hydrogen bonding nitrile groups such as copolymers of the formulae:

l soar! and the like; hydrogen bonding halide groups such as, for example, polyvinyl fluoride, and the like; and miscellaneous polymeric materials such as, for example, polyvinyl N-methyl-N,N'-dimethylurea, polyvinylpyridine, styrene/ maleic anhydride copolymers, including appropriately synthetically modified naturally occuring polymers such as appropriately modified polysaccharide and proteinaceous polymers including chemically modified cellulosic and starch polymeric materials.

In order to minimize reduction in the integrity of the layer of the film unit in which the polymer-silver halide developing agent complex is disposed and disadvantageous optical effects if disposed in the exposure path of the film unit, the polymer complex Will be disposed in the film unit layer as a particulate dispersion possessing a maximum particle size not substantially in excess of about 1;: and for most efficient employment will be disposed contiguous silver halide crystals with respect to which it is designed to interact during processing. The preferred distribution, i.e., within one or more of the silver halide layers, avoids disposition of excess polymer complex material Within the film unit to obviate, or reduce, diffusion losses effected during processing of the unit.

In general, the concentration of polymer-silver halide developing agent complex to be employed per silver halide/ dye developer unit Will range from an effective mole ratio of about 1:1 in those instances wherein the dye developer possesses relatively low silver halide developing potential in and of itself to considerably less complex in instances of high energy dye developers, the optimum concentration for a selected system being readily ascertained empirically by simple photometric screening procedures of the art. As disclosed in, for example, U.S. Pat. No. 3,438,- 775, the dye developer will ordinarily be disposed in the film unit in a concentration Within the range of about 0.01 to 5 mgs. of dye per mg. of silver and generally in a polymeric matrix in a concentration within the range of about 0.1 to 25 mgs. of dye per mg. of polymer, by weight, and, when present as a solid diSpeI'siOn of dye developer, in a particulate form possessing a particle size distribution wherein 50% and preferably 75 of the dye possesses a diameter below about 111.

Employment of diffusion transfer color process film units possessing the polymer-silver halide developing complex has been discovered to provide markedly increased film unit storage stability by reason of the decreased proclivity of the polymer complex to fog the units silver halide layers when compared With a particulate dispersion of the silver halide developing agent in the active developing species from, or with, an organic solvent dispersion of the agent as disclosed in French Pat. No. 1,313,086 wherein the aqueous film unit medium acts to extract or leach a proportion of the agent intended to be retained during storage totally within the organic phase. The decreased proclivity of the polymer complex to fog the silver halide accordingly facilitates, in contradistinction to the procedures of the prior art including those presently employed commercially, practical distribution of the developing agent in the silver halide layer or layers of the unit contiguous the photosensitive silver halide grains, the most efiicient placement for optimization of its dye image transfer control function in the dye transfer process. As previously mentioned such distribution also optimizes the quantity of agent to be disposed in the film unit to effect the control function desired in the selected system by avoiding diffusion losses resultant from the prior art practical necessity of distributing such agent in a layer other than the silver halide layer within which it is destined to interact, specifically including losses attributed to agent ultimately obtaining residence in the receptor stratum of the unit with its potential of providing oxidation and/or degradation product stain or discoloration to the receptor layer and resultant transfer dye image degradation.

In addition, it has been noted that the polymer-silver halide developing agent specifically avoids the problem of crystal accretion existing in situations wherein solid dispersions of silver halide developing agent are disposed Within the film unit With its concomitant production of developing agent crystals exceeding the maximum size which may be effectively tolerated within the optical exposure path of the unit, e.g., by reason of the light scattering effect of such crystals and its corresponding reduction in the signal resolution capacity of the unit, degradation of image recordation capacity and quality and that of the corresponding dye transfer image construction.

Recognizing that although efiicient utilization of the polymer complex in terms of its active species film unit coverage requirement decreases the excess quantities of auxiliary silver halide developing agent, silver halide, dye developer and photographic adjuvants necessary to factor out inefficient dye transfer process performance, most importantly control of the imagewise generation of and transfer of dye developer material is most accurately accomplished employing polymer-silver halide developing agent complex distribution the active species of which generated during processing are readily available to individually contribute to selective generation and control of the transfer of the dye developer image-forming components.

The photoresponsive silver halide material employed in the practice of the present invention will, as previously described, comprise a crystal of a compound of silver, for example, one or more of the silver halides, such as photosensitive silver chloride, silver iodide, silver bromide, and preferably, mixed silver halides, such as silver chlorobromide, silver iodochloride, silver iodobromide or silver iodochlorobromide, of varying halide ratios and the silver concentrations dispersed in a processing composition permeable binder material such as gelatin and the like, most preferably silver iodobromide and iodochlorobromide, particularly that comprising about 0.1 to 9% iodide by weight of silver.

The preferred silver halide type photosensitive layers employed for the fabrication of the photographic film unit, may be prepared by reacting a Water-soluble silver salt, such as silver nitrate, with at least one water soluble halide, such as ammonium, potassium or sodium chloride, preferably together with corresponding iodide and bromide, in an aqueous solution of a peptizing agent such as colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual Water-soluble salts, for example, employing the preferred gelatin matrix material, by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or, alternatively, employing any of the various floc systems, or procedures, adapted to effect removal of undesired components, for

example, the procedures described in US. Pats. Nos. 2,614,928; 2,614,929; 2,728,662, and the like; after ripening the dispersion at an elevated temperature in combination with the addition of gelatin or such other polymeric material as may be desired and various adjuncts, for example, chemical sensitizing agents of US. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. B., Photography Its Materials and Processes, 6th ed., 1962.

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

As the binder for the photoresponsive material, the aforementioned gelatin may be, in whole or in part, replaced with some other natural and/ or synthetic processing composition permeable polymeric material such as albumin; casein; or zein or resins such as cellulose derivative, as described in US. Pats. Nos. 2,322,085 and 2,541,- 474; vinyl polymeric such as described in an extensive multiplicity of readily available U .S. and foreign patents or the photoresponsive material may be present substantially free of interstitial binding agent as described in US. Pats. Nos. 2,945,771; 3,145,566; 3,142,567; Newman, Comment on Non-Gelatin Film, B. I. O. P., 434, Sept. 15, 1961; and Belgian Pats. Nos. 642,557 and 642,558.

In preferred embodiments of the present invention, the photosensitive silver halide emulsions employed will be emulsions adapted to provide a Diffusion Transfer :Process Exposure Index about 50, which Index indicates the correct exposure rating of a dilfusion transfer color process at which an exposure meter, calibrated to the ASA Exposure Index, must be set in order that it give correct exposure data for producing color transfer prints of satisfactorily high quality. The Dilfusion Transfer Process Exposure Index is based on a characteristic H & D curve relating original exposure of the photosensitive silver halide emulsions to the respective curve densities forming the resultant transfer image. Thus, the Diffusion Transfer 'Exposure Index is based on the exposure to which the photosensitive silver halide emulsions, for use in color diffusion transfer processes, must be subjected in order to obtain an acceptable color transfer image by that process and is a direct guide to the exposure setting to be entered in a camera in order to obtain proper exposure of the film unit.

In a preferred embodiment of the present invention, the means for interposing the processing composition selected intermediate the reception layer and the silver halide layer comprises a rupturable container retaining a processing composition comprising the solvent and pH concentrations required fixedly positioned and extending transverse a. leading edge of the film unit to effect, upon application of compressive pressure, discharge of the processing composition intermediate the reception layer and the photosensitive silver halide layer next adjacent. in such embodiment the opacifying agent is preferably disposed within the processing composition, as retained in the rupturable container, for distribution as a component of such composition intermediate the reception and silver halide layers, subsequent to selective exposure of the film unit.

'Multicolor images may be obtained using dye developers in the diffusion transfer process of the present invention by several techniques. One such technique contemplates obtaining multicolor transfer images utilizing employment of an integral multilayer photosensitive element, such as is disclosed in aforementioned US. Pat. No. 3,415,644 wherein at least two selectively sensitized photosensitive strata, superposed on a single support, are processed, simultaneously and Without separation, with a single, common image-receiving layer. A suitable arrangement of this type comprises the opaque support carrying a red-sensitive silver halide stratum, a greensensitive silver halide stratum and a blue-sensitive silver halide stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver halide stratum, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide strata. Each set of silver halide strata and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

In a preferred embodiment of the present invention, the film unit is specifically adapted to provide for the production of a multicolor dye transfer image and the photosensitive laminate comprises, in order of essential layers, the dimensionally stable opaque layer; at least two selectively sensitized silver halide strata each having dye developer of predetermined color associated therewith, which are soluble and diffusible in processing composition as a function of the point-to-point degree of exposure of the respective associated silver halide stratum; a polymeric layer dyeable by the dye developer; and a dimensionally stable transparent layer.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and orthoand paraamino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

The dye developers are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, that is, the previously menitoned cyan, magenta and yellow. The dye developers employed may be incorporated in the respective silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide stratum. Specifically, the dye developer may, for example, be in a coating or layer behind the respective silver halide stratum and such a layer of dye developer may be applied by use of a coating solution containing about 0.5 to 8%, by weight, of the respective dye developer distributed in a film-forming natural, 'or synthetic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the chosen diffusion transfer fluid processing composition.

The silver halide strata comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separateregions of the spectrum and each has associated therewith a dye which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at a first pH possessing, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the silver halide strata, and its associated dye, is separated from the remaining strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers.

In such preferred embodiment of the invention, the silver halide strata comprises photosensitive silver halide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to microns in thickness; the dyeable polymeric layer is transparent and about 0.25 to 0.4 mil. in thickness; and each of the dimensionally stable opaque and transparent layers are alkaline solution impermeable, processing composition vapor permeable and about 2 to 6 mils. in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

Although in point of fact, the dimensionally stable layers employed in the practice of the present invention may possess a vapor transmission rate of 1 or less gms./24 hrs/100 in. /mil., in a preferred embodiment of the present invention, the layers employed will possess a vapor transmission rate for the selected processing composition solvent averaging not less than about 100 gms./24 hrs./ 100 in. /mil., most preferably in terms of the preferred solvent, Water, a vapor transmission rate averaging in excess of about 300 gms. of water/24 hrs/100 in. /mil., and may advantageously comprise a microporous polymeric film possessing a pore distribution which does not unduly interfere with the dimensional stability of the layers or, Where required, the optical characteristics of such layers. Such pore distribution may comprise, for example, an average pore diameter of from about 20 microns to about 100 microns and a pore volume of about 3% to about 7%.

In a particularly preferred embodiment of the present invention, the preferred solvent, water, may be employed in a weight/weight ratio of about 1:10 to 1:20 dye to water at a ratio of about 1:3 to 1:10 liquid permeable polymer to water and most preferably will be fabricated to comprise about 300 to 1300 mgs./ft. liquid permeable polymeric binder material, about 200 to 400 mgs./ft. dye and about 5000 mgs./ft. water.

The dimensionally stable layers are designed so that there is no liquid flow through the layers while allowing the vapor of the processing composition solvent to pass by diffusion from the evaporating liquid body and the operational efiiciency of the film unit is directly dependent upon the nature and quality of the vapor permeable membrauce characteristics of the layers selected. The vapor transmission characteristics desired are directed to maximization of the rate at which the required quantity of processing solvent is effectively evacuated from the film unit subsequent to substantial dye transfer image formation by diffusion transfer processing, commensurate with maintaining the liquid impermeability and dimensional stability characteristics of the layers. Thus, the layers should possess the maximum vapor transmission capacity which permits the passage of processing composition solvent vapor, and any gas dissolved therein, at its vapor pressure, without allowing passage of fluid processing composition. The layers employed in accordance with the present invention therefor should be as thin as possible for solvent vapor transmission efiiciency yet retain sufficient strength to provide stability to and resist chemical and physical degradation of the film unit under conditions of use.

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, the respective silver halide/dye developer units of the photo-sensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable opaque layer, the yellow dye developer/blue-sensitive emulsion unit most distant from the opaque layer and the magenta dye developer/greensensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.

Reference is now made to FIGS. 1 through 7 of the drawings wherein there is illustrated a preferred film unit of the present invention and wherein like numbers, appearing in the various figures, refer to like components.

As illustrated in the drawings, FIG. 1 sets forth a perspective view of the film unit, designated 10, and each of FIGS. 2 through 7 illustrate diagrammatic cross-sectional views of film unit 10, along the stated section lines 22, 3-3, 55 and 7-7, during the various depicted stages in the performance of a photographic diffusion transfer process as detailed hereinafter.

Film unit 10 comprises rupturable container 11, retaining, prior to processing, aqueous processing composition 12, and photosensitive laminate 13 including, in order, dimensionally stable opaque layer 14, preferably an actinic radiation-opaque flexible sheet material; cyan dye developer layer 15; red-sensitive silver halide emulsion layer 16; interlayer 17; magenta dye developer layer 18; green-sensitive silver halide emulsion layer 19; interlayer 20; yellow dye developer layer 21; blue-sensitive silver halide emulsion layer 22; auxiliary layer 23, which may contain an auxiliary silver halide developing agent; imagereceiving layer 24; spacer layer 25; neutralizing layer 26; and dimensionally stable transparent layer 27, preferably an actinic radiation transmissive flexible sheet material.

The structural integrity of laminate 13 may be maintained, at least in part, by the adhesive capacity exhibited between the various layers comprising the laminate at their opposed surfaces. However, the adhesive capacity exhibited at an interface intermediate image-receiving layer 24 and the silver halide emulsion layer next adjacent thereto, for example, image-receiving layer 24 and auxiliary layer 23 as illustrated in FIGS. 2 through 7, should be less than that exhibited at the interface between the opposed surfaces of the remainder of the layers forming the'laminate, in order to facilitate distribution of processing solution 12 intermediate the stated image-receiving layer 24 and the silver halide emulsion layer next adjacent thereto. The laminates structural integrity may also be enhanced or provided, in whole or in part, by providing a binding member extending around, for example, the edges of laminate 13, and maintaining the layers comprising the laminate intact, except at the interface between layers 23 and 24 during distribution of processing composition 12 intermediate those layers. As illustrated in the figures, the binding member may comprise a pressure-sensitive tape 28 securing and/or maintaining the layers of laminate 13 together at its respective edges. Tape 28 will also act to maintain processing solution 12 intermediate image-receiving layer 24 and the silver halide emulsion layer next adjacent thereto, up application of compressive pressure to pod 11 and distribution of its contents intermediate the stated layers. Under such circumstances, binder tape 28 will act to prevent leakage of fluid processing composition from the film units laminate during and subsequent to photographic processing.

Rupturable container 11 may be of the type shown and described in any of US. Pats. Nos. 2,543,181; 2,634,- 886; 3,653,732; 2,723,051; 3,056,492; 3,056,491; 3,152,- 515; and the like. In general, such containers will comprise a rectangular blank of fiuidand air-impervious sheet material folded longitudinally upon itself to form two walls 29 which are sealed to one another along their longitudinal and end margins to form a cavity in which processing composition 12 is retained. The longitudinal marginal seal 30 is made weaker than the end seals 31 so as to become unsealed in response to the hydraulic pressure generated within thhe fluid contents 12 of the container by the application of compressive pressure to walls 29 of the container.

As illustrated in FIGS. 1, 2 and 3, container 11 is fixedly positioned and extends transverse a leading edge of photosensitive laminate 13 whereby to effect unidirectional discharge of the containers contents 12 between image-receiving layer 24 and the stated layer next adjacent thereto, upon application of compressive force to container 11. Thus, container 11, as illustrated in FIG. 2, is fixedly positioned and extends transverse a leading edge of laminate 13 with its longitudinal marginal seal 30 directed toward the interface between imagereceiving layer 24 and auxiliary layer 23. As shown in FIGS. 1, 2 and 4, container 11 is fixedly secured to laminate 13 by extension 32 of tape 28 extending over a portion of one wall 29 of the container, in combination with a separate retaining member such as illustrated retaining tape 33 extending over a portion of laminate 13s surface generally equal in area to about that covered by tape 28.

As illustrated in FIGS. 1, 2 and 4, extension flap 32 of tape 28 is preferably of such area and dimensions that upon, for example, manual separation of container 11 and tape 33, subsequent to distribution of processing composition 12, from the remainder of film unit 10, flap 32 may be folded over the edge of laminate 13, previously covered by tape 33, in order to facilitate maintenance of the laminates structural integrity, for example, during the flexations inevitable in storage and use of the processed film um't, and to provide a suitable mask or frame, for viewing of the transfer image through the picture viewing area of transparent layer 27.

The fluid contents of the container preferably comprise an aqueous alkaline solution having a pH and solvent concentration at which the dye developers are soluble and diffusi'ble and contains inorganic light-reflecting pigment and at least one optical filter agent at a pH above the pKa of such agent in a quantity sufficient, upon distribution, effective to provide a layer exhibiting optical transmission density about 6.0 and optical reflection density about 1.0 to prevent exposure of photosensitive silver halide emulsion layers 16, 19 and 22 by actinic radiation incident on dimensionally stable transparent layer 27 during processing in the presence of such radiation and to afford immediate viewing of dye image formation in image-receiving layer 24 during and subsequent to dye transfer image formation. Accordingly, the film unit may be processed, subsequent to distribution of the composition, in the presence of such radiation, in view of the fact that the silver halide emulsion or emulsions of laminate are appropriately protected by incident radiation, at one major surface of the opaque processing composition and at the remaining major suface by the dimensionally stable opaque layer. If the illustrated binder tapes are also opaque, edge leakage of actinic radiation incident on the emulsion or emulsions will also be prevented.

The selected reflecting pigment should 'be one providing a background suitable for viewing the dye developer transfer image formed in the dyeable polymeric layer. In general, while substantially any reflecting agent may be employed, it is preferred that a reflecting agent be selected that will not interfere with the color integrity of the dye transfer image, as viewed by the observer, and, most preferably, an agent which is aesthetically pleasing to the viewer and does not provide a background noise signal degrading, or detracting from, the information content of the image. Particularly desirable reflecting agents will be those providing a white background, for viewing the transfer image, and specifically those conventionally employed to provide background for reflection photographic prints and, especially those agents possessing the optical properties desired for reflection of incident radiation.

As examples of reflecting pigments adapted for employment in the practice of the present invention, mention may be made of barium sulfate, zinc sulfide, titanium dioxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica, and the like.

A particularly preferred reflecting agent comprises titanium dioxide due to its highly effective reflection properties. In general, in such preferred embodiment, based upon percent titanum dioxde (weight/volume) a processing composition containing about 1500 to 4000 mgs./ft. titanium dioxide dispersed in 100 cc. of water will provide a percent reflectance of about to In the most preferred embodiments, the percent reflectance particularly desired will be in the order of about 85%.

In embodiments wherein the dispersion comprises a preformed layer positioned intermediate the reception layer and next adjacent silver halide layer, the pigment layer will be sufliciently transparent to allow transit of exposing radiation through the pigment layer and may comprise titanium dioxide reflecting agent possessing a particle size distribution averaging about 0.2 micron in diameter and preferably about 0.05 micron in diameter as initially present preceding exposure of the film unit, which preferred materials, upon contact with aqueous alkaline processing composition, preferably aggregate to provide particles possessing a diameter about 0.2 micron in diameter and will be coated at a coverage of about 200 to 1000 mgs./ft. Specifically, the reflecting agent will be present in a quantity insuflicient to prevent exposure of the emulsion layers by actinic radiation incident of the di mensionally stable transparent layer of the film unit but in a concentration sufficient, subsequent to processing, to mask dye developer associated with the silver halide emulsion strata from the dye transfer image. In the preferred construction of such embodiment, the pigment such as titanium dioxide will be initally present in a relatively small particle size to provide unexpectedy efiicient transit of radiation through the reflecting layer during exposure which upon contact with an alkaline processing composition and aggregation of the pigment partcles provides efficient light reflectivity and masking capacity subsequent to such aggregation.

In general, the reflecting agents to be employed are those which remain substantially immobile within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiffusible inorganic pigment dispersions within the layer in which they are disposed.

Where desired, reflecting agent pigment may thus be distributed in whole or in part within a processing composition permeable polymeric matrix such as gelatin and/ or any other such polymeric matrixes as are specifically denoted throughout the specification as suitable for employment as a matrix binder and may be distributed in one or more of the film unit layers which may be separated or contiguous, intermediate the image-receiving layer and next adjacent silver halide layer, provided that its distribution and concentration is effective to provide, the denoted post-processing masking function, and/or in whole or in part the reflecting agent may be ultimately disposed within the porcessing composition residuum located intermediate the image-receiving layer and next adjacent silver halide emulsion strata and associated dye imageforming material.

The optical filter agent selected should be one exhibiting, at a pH above its pKa, maximum spectral absorption of radiation at the wavelengths to which the film units photosensitive silver halide layer or layers are sensitive and should be substantially immobile or nondifl'usible within the pigment dispersion, during performance of its radiation filtration function, in order to maintain and enhance the optical integrity of the dispersion as a radiation filter unit functioning in accordance with the present invention, and to prevent its diffusion into and localized concentration within the image-receiving layer thereby decreasing the efficiency of the reflecting pigment dispersion as a background against which image formation may be immediately viewed, during the initial stages in the diffusion transfer processing of the film unit, by filter agent absorption of dispersion reflected visible radiation prior to reduction in the environmental pH below the pKa of the agent. Commensurate with the spectral sensitivity range of the associated silver halide layer or layers, the optical filter agent selected may comprise one or more filter dyes possessing obsorption complementary to such silver halide layers in order to provide effective protection against physical fog providing radiation during processing. Recognizing that the filter agent absorption will derogate from image-viewing characteristics by contaminating reflecting pigment background, the selected agents should be those exhibiting major spectral absorption at the pH at which processing is effected and minimal absorption at a pH below that which obtains during transfer image formation. Accordingly, the selected optical filter agent or agents should possess a pKa below that of the processing pH and above that of the environmental pH subsequent to transfer image formation, and will be preferably selected for employment in the minimum concentration necessary to provide an optical transmission density about 6.0, at wavelengths at which the silver halide layer is maximally responsive, and an optical reflection density about 1.0 at such wavelengths.

As specific examples of such pH-sensitive optical filter agents adapted for employment in the practice of the present invention, reference is directed to the agents set forth in aforementioned copending US. patent application Ser. No. 43,782, filed June 5, 1970, incorporated herein by reference.

In general, preferred agents, both opacifying and filter, are those which remain immobile within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiifusible materials.

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor difl'usion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of untilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

In the performance of the diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 13, incident on the laminates exposure surface, as illustrated in FIG. 3.

Subsequent to exposure, as illustrated by FIGS. 2 and 4,

film unit 10 is processed by being passed through opposed suitably gapped rolls 35 in order to apply compressive pressure to frangible container 11 and to effect rupture of longitudinal seal 30 and distribution of alkaline processing composition 12, possessing inorganic light-reflecting pigment and optical filter agent at a pH above the pKa of the filter agent and a pH at which the cyan, magenta and yellow dye developers are soluble and diffusible as a function of the point-to-point degree of exposure of red-sensitive silver halide emulsion layer 16, green-sensitive silver halide emulsion layer 19 and blue-sensitive silver halide emulsion layer 22, respectively, intermediate image-receiving layer 24 and auxiliary layer 23.

Alkaline processing composition 12 permeates emulsion layers 16, 19, and 22 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 15, 18 and 21, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nondilfusible oxidized form, thereby providing imagewise distributions of mobile, soluble and diffusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to dyeable polymeric layer 24 to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the reflecting pigment present in processing composition residuum 12 masking cyan, magenta and yellow dye developer remaining associated with blue-sensitive emulsion layer 22, green-sensitive emulsion layer 19 and red-sensitive emulsion layer 16. Subsequent to substantial transfer image formation, a sufiicient portion of the ions comprising aqueous alkaline processing composion 12 transfer by diffusion, through permeable polymeric reception layer 24, permeable spacer layer 25 to polymeric neutralizing layer 26 whereby the environmental pH of the system decreases as a function of neutralization to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are substantially nonditfusible to thereby provide a stable multicolor dye transfer image and discharge of the pH-sensitive optical filter agent by reduction of the pH substantially below the pKa of such agent to thereby provide maximum reflectivity in terms of the pigment concentration present.

The alkaline solution component of the processing composition, positioned intermediate the photosensitive element and the image-receiving layer, thus permeates the emulsions to initiate development of the latent images contained therein. The respective associated dye developers are mobilized in unexposed areas as a consequence of the development of the latent images. This mobilization is apparently, at least in part, due to a change in the solubility characteristics of dye developer upon oxidation and especially as regards its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsions, the associated dye developer is diffusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the point-to-point degree of exposure of the silver halide emulsion. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise dififusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image.

Subsequent to distribution of processing composition 12, container 11 may be manually dissociated from the remainder of the film unit, as described above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details therein set forth and are intended to be illustrative only.

Film units similar to that shown in the drawings ma be prepared, for example, by formulating a dispersion of a polymer-silver halide developing agent by dissolving about 120 gms. of 4-methylphenylhydroquinone in about 1200 cc. of isopropanol and about 240 cc. of about 40% (weight/weight) polyvinylpyrrolidone sold by GAP Corporation, Binghamton, N.Y., under the grade designation K-15 [M.W. about 5,000] in about 17,900 cc. of water; adding the organic solution to the aqueous solution at room temperature, under agitation and at a rate of about 20 cc. per minute; adding in order about 1400 cc. of 0.1 M. ammonium nitrate and about 200 cc. of 0.1 M. sodium acetate at a pH of 5.4 under agitation; ceasing agitation and collecting the insoluble polyvinyl pyrrolidone-4- methylphenylhydroquinone formed; washing the polymersilver halide developing agent complex with about 4000 cc. of 0.001 M. ammonium nitrate; dispersing the polymer complex in water with Lomar D (trade name of Nopeo Chemical Co., Newark, NJ. for a dispersant comprising the sodium salt of condensed mononaphthalene sulfonic acid) dispersant at a concentration of about 7% complex based on dry weight of the 4-methylphenyl-hydroquinone and about 3% dispersant; sonifying the dispersion with a 1000-watt sonifier for about one hour; allowing the dispersion to stand for about two hours; adding decanted dispersion to an aqueous gelatin solution at a ratio of about 1-4-methylphenylhydroquinone to 0.5 gelatin; and passing the dispersion sequentially through a colloid mill at a mil. gap.

The film unit itself may then be prepared, for example, by coating, in succession, on a 5 mil. opaque polyester film base, the following layers:

(1) A layer of the cyan dye developer in. I

Hz N: N l ?H: OH @sm-nn-pn on, H0 l 20 dispersed in gelatin and coated at a coverage of about'98 mgs./ft. of dye and about 87 mgs./ft. of gelatin;

(2) A red-sensitive gelatino-silver iodobromide emulsion coated at a coverage of about 140 mgs./ft. of silver and about mgs./ft. of gelatin;

(3) A layer of butyl acrylate/diacetone acrylamide/ styrene/methacrylic acid I (60/ 30/4/ 6) and polyacr'ylamide coated in a ratio of about 32:1, respectively, at a coverage of about mgs./ft. is

(4) A layer of the magenta dye developer /N-SO N=N CH1 Ho-cm-cm p I o 0, F

dispersed in gelatin and coated at a coverage of 71 mgs./ ft. of dye and about 104 mgs./l?t. of gelatin;

(5) A green-sensitive gelatin0 silver iodobromide emulsion comprising polyvinylpyrrolidbne 4 methylphenylhydroquinone complex coated at a coverage .of about80 mgs./ft. of silver, 40 mgs./f t. of. gelatin and. about 6 mgsJft. of complex; 1

(6) A layercomprising butylacrylate/diacetone acrylamide/styrene/methacrylic acid (6 0/ 30/4/ 6) and poly: acrylamide coated in a ratio of about 8:1, respectively, at a coverage of about 50 mgs./ft.

(7) A layer of the yellow dye developer C-CHz-CH dispersed in gelatin and coated at a coverage of about 80 mgs./ft. of dye, and about 117 mgs./ft. of gelatin;

(8) A blue-sensitive gelatino-silver iodobromide emulsion comprising polyvinylpyrrolidone 4 methylphenylhydroquinone complex coated at a coverage of about 80 acid copolymer and polyvinyl alcohol at a coverage of about 1400 mgs /ft. to provide a polymeric acid layer;

(2) A graft copolymer of acrylamide and diacetone acrylamide on a polyvinyl alcohol backbone in a molar ratio of 1:3.221 at a coverage of about 800 mgs./ft. to provide a polymeric spacer layer; and

(3) A 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of about 900 mgs./ft. and including about mgs./ft. phenyl mercapto tetrazole, to provide a polymeric image-receiving layer.

The two components thus prepared may then be taped together in laminate form, at their respective edges, by means of a pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant laminate.

A rupturable container comprising an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution comprising:

Gms.

Potassium hydroxide 11.20 Hydroxyethyl cellulose (high viscosity) [commercially available from Hercules Powder Co., Wilmington, Delaware, under the trade name Natrasol 250] 3.40 N-phenethyl-a-picolinium bromide 2.70 Benzotriazole 1.15 Titanium dioxide 50.00

Water, 100.00 cc.

may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes interconnecting the respective containers and laminates, such that, upon application of compressive pressure to a container, its contents may be distributed, upon rupture of the containers marginal seal, between the polymeric image-receiving layer and next adjacent gelatin layer.

The photosensitive composite film units may be exposed through radiation incident on the transparent cellulose triacetate layer and processed by passage of the exposed film units through appropriate pressure-applying members, such as suitably gapped, opposed rolls, to effect rupture of the container and distribution of its contents. Subsequent to processing, the multicolor dye transfer image formation may be viewed through the transparent polyester layer against the titanium dioxide back- 22 ground provided by distribution of the pigment containing processing composition between layer 9 and the polymeric image-receiving layer. Multicolor dye transfer image formation will be found to be substantially completed and exhibiting the required color brilliance, hues, saturation and isolation, within a period of approximately seconds.

The gelatino silver iodobromide emulsions employed will possess the silver halide distribution gradient detailed hereinbefore and may be prepared as previously detailed and chemically sensitized, at about 56 C., pH 5 and pAg 9, by the addition of a sensitizing amount of a solution containing 0.1 gram of ammonium thiocyanate in 9.9 cc. of Water and 1.2 cc. of a solution containing 0.097 gram of gold chloride in 9.9 cc. of water, and a 0.02% aqueous sodium thiosulfate solution. The resultant emulsions may then be appropriately sensitized spectrally by addition of an effective concentration of one or more optical sensitizing dyes dispersed in an appropriate carrier solvent.

By addition of (A) 2.08 gms.

II-Cn n I (I) H (I) H mHas-n (B) 0.52 grns.

and

(C) 1.18 gms.

The pH and solvent concentration of the alkaline processing solution initially employed will possess a pH above the pKa of the optical filter agents where the latter are employed, that is, the pH at which about 50% of the agents are present as the lesser absorbing species and about 50%are present as the greater absorbing species, preferably a pKa of 11 and most preferably about 12 and a pH at which the dye developers employed are soluble and diifusible. Although it has been found that the specific pH to be employed may be readily determined empirically for any dye developer and optical filter agent, or group of dye developers and filter agents, most particularly desirable dye developers are soluble at pHs above 9 and relatively insoluble at pHs below 9, inreduced form, and relatively insoluble at substantially any alkaline pH, in oxidized form, and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated film-forming viscosity-increasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structually stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition.

Neutralizing means, for example, a polymeric acid layer of the type discussed above may be incorporated, as stated, in the film unit of the present invention, to provide reduction of the alkalinity of the processing solution from a pH above the pKa of the optical filter agent selected at which the dyes are soluble to a pH below the pKa of the agent at which the dyes are substantially nonditfusible, in order to advantageously further stabilize and optimize reflectivity of the dye transfer image. In such instance, the neutralizing layer may comprise particulate acid reacting reagent disposed within the film unit or a polymeric acid layer, for example, a polymeric acid layer approximating 0.3 to 1.5 mils. in thickness, positioned intermediate the transparent support and image-receiving layer, and/or the opaque support and next adjacent emulsion/dye unit layer, and the film unit may also contain a polymeric spaced or barrier layer, for example, approximating 0.11 to 0.7 mil. in thickness, next adjacent the polymeric acid layer, opposite the respective support layer, as previously described.

Specifically, the filrn units may employ the presence of a polymeric acid layer such as, for example, of the type set forth in US. Pat. No. 3,362,819 which, most preferably, includes the presence of an inert timing or spacer layer intermediate the polymeric acid layer carried on a support and the image-receiving layer.

As set forth in the last-mentioned patent, the polymeric acid layer may comprise polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, retained in the polymer layer. In the preferred embodiments disclosed, the polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming water-soluble sodium and/or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid half-ester derivatives of cellluose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether/maleic anhydride copolymers; etc.

As previously noted, the pH of the processing composition preferably is of the order of at least 12 to 14 and the pKa of the selected optical filter agents will accordingly preferably be in the order of 13 or greater. The polymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image layer from a pH of about 12 to 14 to a pH of at least 11 or lower at the end of the imbibition period, and preferably to a pH of about 5 to 8 within a short time after imbibition, thus requiring, of course, that the action of the polymeric acid be accurately so controlled as not to interfere with either development of the negative or image transfer of unoxidized dye developers. For this reason, the pH of the image layer must be kept at a functional transfer level, for example, 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to a pH below that at which dye transfer may be accomplished, for example, at least about 11 and preferably about pH 9' to 10. Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of, for example, 12 to 14 until transfer of the necessary quantity of dye has been accomplished. The subsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an un: desired reduction in positive image density, the acid groups are disclosed to be so distributed in the polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct-relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the polymer layer may be effected by mixing acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only an acid polymer but selecting one having a relatively lower proportion of acid groups. These embodiments are illustrated, respectively, in the cited copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acid may contain a water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed. As examples of cellulose esters contemplates for use, mention is made of cellulose acetate, cellulose acetate butyrate, etc. The particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength and when necessary or desirable, suitable subcoats are employed to help the various polymeric layers adhere to each other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin, acts to time control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It is there stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rapidly once the alkali diffuses through the spacer layer.

As disclosed in aforementioned U.S. Pat. No. 3,362,- 819, the presence of an inert spacer layer was found to be effective in evenning out the various reaction rates over a wide range of temperatures, for example, by preventing premature pH reduction when imbibition is effected at temperatures above room temperature, for example, at 95 to 100 F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture in the polymeric acid layer becomes a function of the alkali diffusion rates.

However, as disclosed in U.S. Pat. No. 3,455,686 preferably the aforementioned rate at which the cations of the alkaline processing composition, i.e., alkali ions, are available for capture in the polymeric acid layer should be decreased with increasing transfer processing temperatures in order to provide diffusion transfer color processes relatively independent of positive transfer image variations over an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusion rate of alkali through a permeable inert polymeric spacer layer increases with increased processing temperature to the extent, for example, that at relatively high transfer processing temperatures, that is, transfer processing temperatures above approximately 80 F., a premature decrease in the pH of the transfer processing composition occurs due, at least in part, to the rapid diffusion of alkali from the dye transfer environment and its subsequent neutralization upon contact with the polymeric acid layer. This was stated to be especially true of alkali traversing an inert spacer layer possessing permeability to alkali optimized to be effective with the temperature range of optimum transfer processing. Conversely, at temperatures below the optimum transfer processing range, for example, temperatures below approximately 40 F., the last-mentioned inert spacer layer was disclosed to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates and to result in maintenance of the transfer processing environments high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.

It is further stated in the last-mentioned U.S. Pat. No. 3,455,686 to have been found, however, that if the inert spacer layer of the print-receiving element is replaced by a spacer layer which comprises a permeable polymeric layer exhibiting permeability inversely dependent on temperature, that is, a polymeric film-forming material which exhibits decreasing permeability to solubilized alkali derived cations such as alkali metal and quaternary ammonium ions under conditions of increasing temperature, that the positive transfer image defects resultant from the aforementioned overextended pH maintenance and/ or premature pH reduction are obviated.

As examples of polymers which were disclosed to exhibit inverse temperature-dependent permeability to alkali, mention may be made of: hydroxypropyl polyvinyl alco hol, polyvinyl methyl ether, polyethylene oxide, polyvinyl oxazolidone, hydroxypropyl methyl cellulose, isopropyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral, partial polyvinyl formal, partial 26 polyvinyl acetal, partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated to generally comprise saturated aliphatic hydrocarbon chains of a molecular weight of at least 1000, preferably of about 1000 to 50,000, possessing a degree of acetalation Within about 10 to 30%, 10 to 30%, 20 to and 10 to 40%, of the polyvinyl alcohols theoretical polymeric hydroxy groups, respectively, and including mixed acetals Where desired.

Where desired, a mixture of the polymers may be employed, for example, a mixture of hydroxypropyl methyl cellulose and partial polyvinyl butyral.

Employment of the detailed and preferred film units of the present invention, according to the herein described color diffusion transfer process, specifically provides for the production of a highly stable transfer image accomplished, at least in part, by effectively obviating the previously discussed disadvantages of the prior art products and processes, by in process adjustment of the environmental processing composition solvent and pH concentration from a solvent and pH concentration at which dye diffusion or transfer is operative to a solvent and pH concentration at which dye transfer is inoperative subsequent to substantial transfer image formation. The stable color transfer image is obtained irrespective of the fact that the film unit is maintained as an integral laminate unit during exposure, processing, viewing, and storage of the unit. Accordingly, by means of the present invention, multicolor transfer images may be provided over an extended processing temperature range which exhibit desired maximum and minimum dye transfer image densities; yellow, magenta and cyan dye saturation; red, green and blue hues; and color separation. These unexpected advantages are in addition to the manufacturing advantages obtained by reason of the present inventions integral color transfer film unit construction and which will be readily apparent from examination of the units parameters, that is, for example, advantages in more efficient utilization of fabricating materials and components, enhanced simplicity of film manufacture and camera design and construction, and more simplified and effectively controlled customer utilization of the unit.

The dimensionally stable support layers referred to may comprise any of the various types of conventional opaque and transparent rigid or flexible materials possessing the requisite liquid impermeability and vapor transmissivity denoted above, and may comprise polymeric films of both synthetic types and those derived from naturally occurring products. Particularly suitable materials include aqueous alkaline solution impermeable, Water vapor permeable, flexible polymeric materials such as vapor permeable polymeric films derived from ethylene glycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate; polyamides; polymethacrylic acid methyl and ethyl esters; cellulose derivatives such as cellulose, acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetate-butyrate; alkaline solution impermeable, water vapor permeable papers; crosslinked polyvinyl alcohol; regenerated cellulose; and the like.

As examples of materials, for use as the image-receiving layer, mention may be made of solution dyeable polymers such as nylon as, for example, N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate with filler as, for exampe, one-half cellulose acetate and one-half oleic acid; gelatin; and other materials of a similar nature. Preferred materials comprise polyvinyl alcohol or gelatin containing a dye modant such as poly-4-vinylpyridine, as disclosed in U.S. Pat. No. $148,061, issued Sept. 8, 1964.

Where desired, development may be advantageously effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in U.S. Pat. No. 3,173,786, issued Mar. 16, 1965.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the first pH and solvent concentration required. When desirable, it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/or in the photosensitive emulsion.

In all examples of this specification, percentages of components are given by weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffusion transfer processes is set forth in aforementioned U.S. Pat. No. 2,983,606 and in the various copending U.S. applications referred to in that patent, especially in the table of U.S. applications incorporated by reference into the patent as detailed in column 27. As examples of additional U.S. patents detailing specific dye developers for photographic transfer process use, mention may also be made of U.S. Pat. Nos. 2,983,605; 2,992,106; 3,047,- 386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,- 061; 3,134,762; 3.134;765; 3,135,604; 3,135,605; 3,135,- 606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl cellulose, as disclosed in U.S. Pat. No. 2,992,- 104; an acylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in U.S. Pat. No. 3,043,692; polymers of N-alkyl-a,B-unsaturated carboxamides and copolymers of N-alkyl-a,fi-carboxamides with N-hydroxyalkyl-a,p-unsaturated carboxamides, as disclosed in U.S. Pat. No. 3,069,263; copolymers of vinylphthalimide and a,}3-unsaturated carboxylic acids, as dis closed in U.S. Pat. No. 3,061,428; copolymers of N-vinylpyrrolidones and a,;3-unsaturated carboxylic acids and terpolymers of N-vinylpyrrolidones, a s-unsaturated carboxylic acids and alkyl esters of o e-unsaturated carboxylic acids, as disclosed in U.S. Pat. No. 3,044,873; copolymers of N,N-dialkyl-a,,8-unsaturated carboxamides with O S-unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N-aryland N- cycloa1kyl-a,,B-unsaturated carboxamides with 11,]3-11I1Sfltl1- rated carboxylic acids, as disclosed in U.S. Pat. No. 3,069,- 296; and the like.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric, or colloidal, matrix such as ball-milling and the like techniques, the preparation of the dye developer dispersion may also be obtained by dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solution distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents, possesses a sufficiently low boiling point or washing where the selected solvent, or solvents, possesses a sufiiciently high differential solubility in the wash medium, for example, water, when measured against the solubility of the remaining composition components, and/ or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types referred to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic color-providing materials in polymeric binders, specifically 28 for the formation component layers of photographic film units, reference may be made to U.S. Pats. Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

Although the invention has been discussed in detail throughout employing dye developers, the preferred image-providing materials, it will be readily recognized that other, less preferred, image-providing materials may be substituted in replacement of the preferred dye developers in the practice of the invention. For example, there may be employed dye image-forming materials such as those disclosed in U.S. Pats. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735; 3,148,062; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294; 3,330,655; 3,347,671; 3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943; etc., wherein color diffusion transfer processes are described which employ color coupling techniques comprising, at least in part, reacting one or more color developing agents and one or more color formers or couplers to provide a dye transfer image to a superposed image-receiving layer and those disclosed in U.S. Pat. No. 2,774,668 and 3,087,817, wherein color diffusion transfer processes are described which employ the imagewise differential transfer of complete dyes by the mechanisms therein described to provide a transfer dye image to a contiguous image-receiving layer, and thus including the employment of image-providing materials in Whole or in part initially insoluble or nondifi'usible as disposed in the film unit which diffuse during processing as a direct or indirect function of exposure.

Although the preceding description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in contiguous coplanar relationship and, specifically, in terms of the preferred tripack type structure comprising a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum having associated therewith, respectively a cyan dye developer, a magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associated therewith, for example, an appropriate dye developer in or behind its respective silver halide emulsion portion. In general, a suitable photosensitive screen will comprise minute red-sensitized emulsion elements, minute green-sensitized emulsion elements and minute blue-sensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black-and-white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression positive image has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be a negative. The expressioin positive image is intended to cover such an image produced on the imagecarrying layer.

It will be recognized that, by reason of the preferred film units structural parameters, the transfer image formed upon directed exposure of the film unit to a selected subject and processing, will be a geometrically reversed image of the subject. Accordingly, to provide transfer image formation geometrically nonreversed, exposure of such film unit should be accomplished through an image reversing optical system such a camera possessing an image reversing optical system.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives sch as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from each other, for example, two or more additives such as plasticizers, intermediate essenbe disposed intermediate the cyan dye image-forming component retaining layer and the dimensionally stable opaque layer.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic diffusion transfer color process film unit which comprises a plurality of layers including a photosensitive layer comprising photosensitive silver halide having associated therewith a dye which is a silver halide developing agent and is diffusible during processing of the unit as a function of the point-to-point degree of said photosensitive layers exposure to incident actinic radiation and a layer adapted to receive dye diffusing thereto, at least one of the layers of said unit comprising a particulate dispersion the particles of which consist essentially of a synthetic polymer benzenoid-silver halide developing agent complex which is dissociable as a function of pH to provide a processing composition soluble silver halide developing agent.

2. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said complex comprises a hydrogen bond complex of a synthetic polymer and a benzenoid silver halide developing agent possessing at least two groups selected from the group consisting of amino and hydroxyl groups, at least one of said amino and hydroxyl groups substituted in at least one of ortho and para positions with respect to one other of said groups.

3. A photographic diffusion transfer color process film unit as defined in claim 2 wherein said complex comprises a hydrogen bond complex of polyvinylpyrrolidone and 4-methylphenylhydroquinone.

4. A photographic diffusion transfer color process film unit as defined in claim 1 including opacifying agent, in a quantity sufficient to mask dye associated with said photosensitive silver halide layer, adapted to be disposed intermediate said photosensitive silver halide layer and said layer adapted to receive dye diffusing thereto.

5. A photographic diffusion transfer color process film unit as defined in claim 1 including means for contacting said photosensitive silver halide layer with a processing composition possessing a pH at which said dye is soluble and diffusible as a function of the point-to-point degree of said photosensitive silver halide layers exposure to incident actinic radiation.

6. A photographic diffusion transfer color process film unit as defined in claim 5 including means for converting the pH of the film unit from said pH at which said dye is soluble and diffusible as a function of said photosensitive silver halide layers exposure to incident actinic radiation to a second pH at which said dye is substantially nondiffusible, subsequent to substantial diffusion of solubilized dye to said layer adapted to receive said dye diffusing thereto.

7. A photographic diffusion transfer color process film unit as defined in claim 5 wherein said means for contacting said photosensitive silver halide layer with said processing composition comprises a rupturable container retaining said processing composition positioned extending transverse an edge of the film unit to effect, upon application of compressive pressure to said container, discharge of said containers processing composition contents into contact with said photosensitive silver halide layer.

8. A photographic diffusion transfer color process film unit as defined in claim 7 wherein said rupturable container retaining said processing composition is adapted, upon application of compressive pressure to the container, to discharge the containers processing composition contents intermediate said photosensitive silver halide layer and the layer adapted to receive dye diffusing thereto.

9. A photographic diffusion transfer color process film unit as defined in claim 8 wherein said processing composition includes opacifying agent in a quantity sufficient to mask dye associated with said photosensitive silver halide layer.

10. A photographic diffusion transfer color process film unit as defined in claim 9 including a dimensionally stable opaque layer positioned contiguous the surface of said photosensitive silver halide layer opposite said layer adapted to receive dye diffusing thereto.

11. A photographic diffusion transfer color process film unit as defined in claim 10 including a dimensionally stable transparent layer positioned contiguous the surface of said layer adapted to receive dye diffusing thereto opposite said photosensitive silver halide layer.

12. A photographic diffusion transfer color process film unit as defined in claim 1 including a dimensionally stable layer positioned contiguous the surface of said photosensitive silver halide layer opposite said layer adapted to receive dye diffusing thereto and additionally including at least two selectively sensitized silver halide layers comprising photosensitive silver halide having a dye which is a silver halide developing agent associated therewith, at least one of said layers of the film unit comprising a particulate dispersion the particles of which consist essentially of a hydrogen bond complex of a synthetic polymer and an aromatic silver halide developing agent possessing at least two groups selected from the group consisting of hydroxyl and amino groups, at least one of the hydroxyl and amino groups substituted in at least one of ortho and para positions on the developing agents aromatic ring with respect to one another of the hydroxyl or ortho groups, which particles are dissociable as a function of pH to provide a processing composition soluble aromatic silver halide developing agent possessing at least two groups selected from the group consisting of'hydroxyl and amino groups, at least one of the hydroxyl or amino groups substituted in one of ortho and para positions with respect to one other of the hydroxyl and amino groups.

13. A photographic diffusion transfer color process film unit as defined in claim 12- wherein each of the selectively sensitized silver halide layers possesses predominant spectral sensitivity to separate regions of the spectrum and the dye associated with each of said silver halide layers possesses a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated silver halide layer.

14. A photographic diffusion transfer color process film unit as defined in claim 13 which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, a dimensionally stable opaque layer; at least two selectively sensitized silver halide emulsion layers possessing predominant spectral sensitivity to separate regions of the visible 31 electromagnetic spectrum, each of said emulsion layers having associated therewith a dye which is a silver halide developing agent and is soluble and diffusible, in alkaline processing composition, at a first pH, possessing a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated emulsion layer; an alkaline solution permeable and dyeable polymeric layer; a polymeric layer possessing acid capacity effective subsequent to substantial dye transfer image formation in said dyeable polymeric layer to reduce alkaline processing composition possessing said first pH at which said dyes are soluble and difi'usible to a second pH at which said dyes are substantially nondilfusible; a dimensionally stable transparent layer; and means securing the layers in substantially fixed relationship, at least one of said layers comprising a substantially water-insoluble particulate dispersion the particles of which consist essentially of a hydrogen bond complex of a synthetic polymer and a dihydroxyphenyl or dihydroxynaphthyl silver halide developing agent which is dissociable as a function of pH upon contact of the complex with aqueous alkaline processing composition to provide a processing composition soluble dihydroxyphenyl or dihydroxynaphthyl silver halide developing agent, and a rupturable container retaining an alkaline processing composition possessing said first pH at which said dyes are soluble and ditfusible and opacifying agent in a quantity sufficient to mask dye associated with said selectively sensitized silver halide emulsion layers, said rupturable container positioned and extending transverse an edge of the photosensitive element to effect unidirectional discharge of the containers alkaline processing composition intermediate the dyeable polymeric layer and the selectively sensitized silver halide emulsion layer next adjacent thereto.

15. A photographic diffusion transfer color process film unit as defined in claim 14 adapted to be processed by passage of said unit between a pair of juxtaposed pressure-applying members and which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, in sequence, a dimensionally stable alkaline solution impermeable opaque layer; a red-sensitive silver halide emulsion layer having associated therewith cyan dye; a greensensitive silver halide emulsion layer having associated therewith magenta dye; a blue-sensitive silver halide emulsion layer having associated therewith a yellow dye, each of said cyan, magenta and yellow dyes being silver halide developing agents soluble and difiusible, in alkaline processing composition, at a first pH, at least one of said blue-, greenand red-sensitive silver halide emulsion layers comprising a substantially water-insoluble particulate dispersion, possessing a particle size not substantially in excess of about I the particles of which consist essentially of a hydrogen bond complex of a synthetic polymer and a 2,5-dihydroxyphenyl silver halide developing agent which is dissociable upon contact with aqueous alkaline processing composition to provide a 2,5-dihydroxyphenyl silver halide developing agent; an alkaline solution permeable and dyeable polymeric layer; a polymeric layer containing suflicient acidifying capacity to effect reduction of a processing composition having said first pH at which said cyan, magenta and yellow dyes are soluble and ditfusible to a second pH at which said cyan, magenta and yellow dyes are substantially nondiffusible; a dimensionally stable alkaline solution impermeable transparent layer;

and means securing said layers substantially in fixed relationship; and

a rupturable container retaining an aqueous alkaline processing composition having said first pH at which said cyan, magenta and yellow dyes are soluble and diffusible and opacifying agent in a quantity sufiicient to mask, upon distribution of the aqueous alkaline processing composition as a layer, intermediate the dyeable polymeric layer and said blue-sensitive silver halide emulsion layer, cyan, magenta and yellow dye associated with said red-, green-, and bluesensitive emulsion layers, said container fixedly positioned and extending transverse an edge of the photosensitive element to effect, upon application of compressive force to said container, unidirectional discharge of the containers aqueous alkaline processing composition contents intermediate said dyeable polymeric layer and said blue-sensitive silver halide emulsion layer.

16. A photographic diffusion transfer color process film unit as defined in claim 15 wherein said 2,5-dihydroxyphenyl silver halide developing agent is toluhydroquinone.

17. A process of forming transfer images in color which comprises, in combination, the steps of:

(a) exposing a photographic film unit which comprises a plurality of layers including a photosensitive element containing a photosensitive silver halide layer having associated therewith a dye which is a silver halide developing agent which is dilfusible during processing as a function of the point-to-point degree of the photosensitive layers exposure to incident actinic radiation and at least one layer of the film unit comprising a particulate dispersion the particles of which consist essentially of a synthetic polymerbenzenoid-silver halide developing agent complex which is dissociable as a function of pH to provide a processing composition soluble silver halide developlng agent;

(b) contacting said photosensitive silver halide emulsion with a processing composition;

(c) eflecting thereby dissociation of said polymersilver halide developing agent complex to provide silver halide developing agent soluble in the processmg composition and development of said photoexposed silver halide layer;

(d) forming thereby an imagewise distribution of diffusible dye as a function of the point-to-point degree of said silver halide layers exposure incident actinic radiation; and

(e) transferring by diffusion at least a portion of said imagewise distribution of said difiusible dye to an image-receiving element dyeable by said dye to provide thereto a dye image in terms of said imagewise distribution.

18. A process of forming transfer images in color as defined in claim 17 wherein the synthetic polymer-silver halide developing agent complex comprises a hydrogen bond complex of an aromatic silver halide developing agent possessing at least two aromatic ring substituents selected from the group consisting of hydroxyl and amino groups, at least one of the hydroxyl or amino groups substituted in at least one of ortho and para positions with respect to one other of said groups and a polymer adapted to hydrogen bond with the silver halide developing agent.

19. A process of forming transfer images in color as defined in claim 18 wherein said photosensitive element comprises in contiguous relationship at least two selectively sensitized silver halide units each having associated therewith a dye which is a silver halide developing agent and is diifusible during processing as a function of the point-to-point degree of'the photoexposure of its associated silver halide layer.

20. A process of forming transfer images in color as defined in claim 19 wherein said selectively sensitized 

